Efficient high power microwave generation using recirculating pulses

ABSTRACT

A high frequency electromagnetic radiation generation device is disclosed that includes a high voltage input, a nonlinear transmission line, an antenna, and a pulse recirculating circuit. In some embodiments, the high voltage input may be configured to receive electrical pulses having a first peak voltage that is greater than 5 kV, and/or may be electrically coupled with the nonlinear transmission line. The antenna may be electrically coupled with the nonlinear transmission line and/or may radiate electromagnetic radiation at a frequency greater than 100 MHz about a voltage greater than 5 kV. The pulse recirculating may be electrically coupled with the high voltage input and the antenna. The pulse recirculating circuit may include a diode; a low pass filter; and a delay line. In some embodiments, unradiated energy from the antenna is directed through the pulse recirculating circuit to the nonlinear transmission line with a delay of less than 100 ns.

BACKGROUND

Producing high power microwave pulses efficiently is challenging due tothe high voltages and high frequencies involved.

SUMMARY

A high frequency electromagnetic radiation generation device isdisclosed that includes a high voltage input, a nonlinear transmissionline, an antenna, and a pulse recirculating circuit. In someembodiments, the high voltage input may be configured to receiveelectrical pulses having a first peak voltage that is greater than 5 kV.In some embodiments, the nonlinear transmission line may be electricallycoupled with the high voltage input. In some embodiments, the antennamay be electrically coupled with the nonlinear transmission line and/ormay radiate electromagnetic radiation at a frequency greater than 100MHz about a voltage greater than 5 kV. The pulse recirculating may becircuit electrically coupled with the high voltage input and theantenna. In some embodiments, the pulse recirculating circuit mayinclude a diode; a low pass filter; and a delay line. In someembodiments, unradiated energy from the antenna is directed through thepulse recirculating circuit to the nonlinear transmission line with adelay of less than 100 ns.

In some embodiments, the nonlinear transmission line may include aplurality of circuit elements that include a nonlinear semiconductorjunction capacitance device and an inductor.

In some embodiments, the high voltage input is coupled with a nanosecondpulser.

In some embodiments, the antenna has an impedance less than about 300Ohms.

A high frequency electromagnetic radiation generation device isdisclosed that includes a high voltage input configured to receiveelectrical pulses having a first peak voltage that is greater than 5 kV;a nonlinear transmission line electrically coupled with the high voltageinput; a high voltage output electrically coupled with the nonlineartransmission line that radiates electromagnetic radiation at a frequencygreater than 100 MHz about a voltage greater than 5 kV; and a pulserecirculating circuit electrically coupled with the high voltage inputand the high voltage output, the pulse recirculating circuit may beconfigured to direct unradiated energy to the nonlinear transmissionline.

In some embodiments, the pulse recirculating circuit comprises a lowpass filter.

In some embodiments, the pulse recirculating circuit comprises at leastone diode.

In some embodiments, the pulse recirculating circuit comprises atransmission line.

In some embodiments, the transmission line comprises a delay line thatintroduces a delay of less than 500 ns in a pulse traveling through thepulse recirculating circuit.

In some embodiments, the nonlinear transmission line comprises aplurality of circuit elements electrically coupled with ground, each ofthe plurality of circuit elements includes a nonlinear semiconductorjunction capacitance device and an inductor, wherein each of theplurality of circuit elements is electrically coupled with at least onecorresponding one of the plurality of circuit elements.

In some embodiments, the high voltage input is coupled with a nanosecondpulser.

A method is also disclosed. The method may include pulsing a highvoltage pulser to produce a first pulse that has a voltage greater than5 kV and a pulse width less than 100 ns; radiating a first plurality ofelectromagnetic radiation pulses from the first pulse at a frequencygreater than 100 MHz and; pulsing the high voltage pulser to produce asecond pulse that has a voltage greater than 5 kV and a pulse width lessthan 100 ns; and radiating a second plurality of electromagneticradiation pulses from the second pulse at a frequency greater than 100MHz. The method may repeatedly recirculate pulses and reradiateadditional electromagnetic radiation pulses from the recirculatedpulses.

In some embodiments, the method may also include recirculating at leasta portion of the first pulse through one or more circuit elements toproduce each of the first plurality of electromagnetic radiation pulses.In some embodiments, the method may also include recirculating at leasta portion of the second pulse through one or more circuit elements toproduce each of the second plurality of electromagnetic radiationpulses.

In some embodiments, the one or more circuit elements comprises acircuit element selected from the list consisting of a diode, a filter,a delay line, and a nonlinear transmission line. In some embodiments,the first plurality of electromagnetic radiation pulses may be radiatedfrom an antenna.

In some embodiments, the first plurality of electromagnetic radiationpulses radiates about a voltage greater than 5 kV; and wherein thesecond plurality of electromagnetic radiation pulses radiate about avoltage greater than 5 kV.

Another method is disclosed. The method may include pulsing a highvoltage pulser to produce a first initial pulse that has a voltagegreater than 5 kV, a pulse width less than 100 ns, and with a firstenergy; radiating a first electromagnetic radiation pulse from a portionof the first initial pulse at a frequency greater than 100 MHz;recirculating a portion of the first initial pulse; pulsing a highvoltage pulser to produce a second initial pulse that has a voltagegreater than 5 kV, a pulse width less than 100 ns, and with a secondenergy, the second energy less than the first energy; combining thesecond initial pulse with the recirculated portion of the first initialpulse to create a combined second pulse; and radiating a secondelectromagnetic radiation pulse from a portion of the combined secondpulse at a frequency greater than 100 MHz.

In some embodiments, the method may also include recirculating a portionof the combined second pulse; pulsing a high voltage pulser to produce athird initial pulse that has a voltage greater than 5 kV, a pulse widthless than 100 ns, and with a third energy, the third energy less thanthe first energy; combining the third initial pulse with therecirculated portion of the combined second pulse to create a combinedthird pulse; and radiating a third electromagnetic radiation pulse froma portion of the combined third pulse at a frequency greater than 100MHz.

In some embodiments, the first initial pulse may be propagated through anonlinear transmission line, the second initial pulse may be propagatedthrough the nonlinear transmission line, and/or the recirculated portionof the first pulse may be propagated through the nonlinear transmissionline. In some embodiments, the portion of the first initial pulse may berecirculated through a transmission line that introduces a delay in theportion of the first initial pulse.

BRIEF DESCRIPTION OF THE FIGURES

These and other features, aspects, and advantages of the presentdisclosure are better understood when the following Detailed Descriptionis read with reference to the accompanying drawings.

FIG. 1 is a block diagram of a nonlinear transmission line microwavegeneration device having a pulse recirculating circuit according to someembodiments.

FIG. 2 is a block diagram of a nonlinear transmission line microwavegeneration device having a pulse recirculating circuit according to someembodiments.

FIG. 3 is a circuit diagram of a nonlinear transmission line with apulse recirculating circuit according to some embodiments.

FIG. 4 is an example flow chart of a process for radiatingelectromagnetic pulses using a pulser with a pulse recirculating circuitaccording to some embodiments.

FIG. 5 is an example flow chart of a process for radiatingelectromagnetic pulses using a pulser with a pulse recirculating circuitaccording to some embodiments.

FIG. 6 is a diagram showing an output on a load and an output from anonlinear transmission line according to some embodiments.

FIG. 7 is a diagram showing energy efficiency versus time using pulserecirculating according to some embodiments.

FIG. 8 is a diagram showing a pulse measured across a load and the pulsemeasured across a load inside the pulse recirculating circuit accordingto some embodiments.

FIG. 9 is a diagram showing a pulse being extinguished overtimeaccording to some embodiments.

FIG. 10 is a circuit diagram of a nonlinear transmission line accordingto some embodiments.

FIG. 11 is a circuit diagram of a nonlinear transmission line accordingto some embodiments.

FIG. 12 is a circuit diagram of a nonlinear transmission line accordingto some embodiments.

FIG. 13 is a circuit diagram of a nonlinear transmission line accordingto some embodiments.

FIG. 14 is an input and output waveform of a nonlinear transmission linemicrowave generation device according to some embodiments.

FIG. 15 is a circuit diagram of a nonlinear transmission line accordingto some embodiments.

FIG. 16 is an input and output waveform of a nonlinear transmission linemicrowave generation device according to some embodiments.

FIG. 17 is a diagram of an input pulse from a high voltage pulser and anoutput pulse after propagating through the nonlinear transmission lineaccording to some embodiments.

FIG. 18 is a zoomed in portion of the diagram shown in FIG. 17 .

DETAILED DESCRIPTION

A high frequency electromagnetic generation device is disclosed. In someembodiments, the high frequency electromagnetic generation device mayinclude a pulse recirculating circuit.

Typical electromagnetic generation system efficiencies can be quite low.For example, these efficiencies can range from a few percent toapproximately 60% for the best klystron systems. High efficiencyklystrons that can generate high peak power more than several hundredkilowatts can be costly and/or require large facility demands which canmake them unsuitable for most applications. The total output efficiencyof a nonlinear transmission line can be quite high (e.g., ˜80%). Not allthis energy, however, is directly converted to RF. Typically, thenonlinear transmission line may only convert 1-10% of the initial pulseenergy to the frequency of interest. The remaining energy in the pulse,which is broadband in nature, is typically lost in the circuittermination resistance. In some embodiments, the energy loss can resultin 100 to 1000 Joules of potential heating.

A pulse recirculating circuit can be used to increase the energyefficiency of an electromagnetic generation system. In some embodiments,the pulse recirculating circuit may include, for example, a filter, adiode, and/or delay line. The pulse recirculating circuit, for example,can be electrically coupled with the load and/or the input of thenonlinear transmission line.

For example, a pulser may provide a pulse having a voltage greater than5 kV (alternatively greater than 10 kV, 20 kV, 50 kV, etc.), a pulsewidth of less than about 100 ns, 50 ns, 25 ns, 10 ns, 5 ns, etc. In someembodiments, a nonlinear transmission line can be used to shorten therise time and/or fall time of the pulse, for example, to less than 50ns, 40 ns, 30 ns, 20 ns, 10 ns, etc. Alternatively or additionally, anonlinear transmission line may generate an electromagnetic pulse.(e.g., 100 MHz-30 GHz). A pulse recirculating circuit can be used torecirculate pulses (or portions of a pulse) through the nonlineartransmission line to radiate another electromagnetic pulse with a givendelay.

In some embodiments, a pulse recirculating circuit may be used inconjunction with a pulser (e.g., a pulser with a nonlinear transmissionline) to radiate a plurality of high frequency electromagnetic pulseswith a frequency of about 100 MHz-30 GHz from a single high voltagepulse from the pulser. In some embodiments, the pulser may generate aplurality of high voltage pulses, which may result in a factor of N highfrequency electromagnetic pulses to be radiated.

FIG. 1 is a block diagram of a high frequency electromagnetic radiationgeneration device 100 having a pulse recirculating circuit 125 accordingto some embodiments. The nonlinear transmission line 115 can include anynonlinear transmission line. The nonlinear transmission line, forexample, may include a nonlinear transmission line described inaccordance with some embodiments of the invention. The nonlineartransmission line, for example, may include a ferromagnetic nonlineartransmission line, gyromagnetic nonlinear transmission line, an LCladder nonlinear transmission line, a lumped element nonlineartransmission line, a dielectric and/or capacitive lumped elementnonlinear transmission line, a parallel plate segmented nonlineartransmission line, a magnetic lumped element nonlinear transmissionline, etc.

The nonlinear transmission line 115, for example, may sharpen the risetime of one or more high voltage pulses (e.g., decrease the rise time,speed up the rise time, etc.) produced by the high voltage pulser 105 tothe point where the output rings. The nonlinear transmission line 115may include the nonlinear transmission line 1000, 1100, 1200, or somevariation thereof.

In some embodiments, for example, a floating output of the high voltagepulser 105 can be electrically coupled with the nonlinear transmissionline 115. And the nonlinear transmission line 115 may be coupled with anoutput that may include the load 120.

In some embodiments, the high frequency electromagnetic radiationgeneration device 100 may or may not include load 120. The load 120, forexample, may be coupled with the output of the nonlinear transmissionline 115. In some embodiments, the load 120 may be an antenna thatoutputs an electromagnetic pulse that oscillates with a frequency of 100MHz-30 GHz. In some embodiments, the antenna may output anelectromagnetic pulse that oscillates around any voltage such as, forexample, 0 volts, 1 kV, 5 kV, 10 kV, 20 kV, etc.

In some embodiments, the high frequency electromagnetic radiationgeneration device 100 may produce electromagnetic radiation in thefollowing frequency bands:

-   -   VHF: 0.03 to 0.3 GHz (Very High Frequency)    -   UHF: 0.3 to 1 GHz (Ultra-High Frequency)    -   L: 1 to 2 GHz    -   S: 2 to 4 GHz    -   C: 4 to 8 GHz    -   X: 8 to 12 GHz

In some embodiments, the load 120 may propagate a high voltage,electromagnetic microwave signal. In some embodiments, the load 120 mayhave an impedance less than about 500, 250, 100, 75, 50, 25, etc. Ohms.In some embodiments, the antenna may have an impedance that is matchedwith NLTL 115.

The load 120 can include an antenna that radiates electromagnetic pulsesand/or may have a low impedance. For example, the impedance of load 120can be less than about 500 Ohms, 250 Ohms, 100 Ohms, 50 Ohms, 25 Ohms,etc. In some embodiments, the pulse recirculating circuit 125 mayintroduce a given delay as the pulse passes through the pulserecirculating circuit 125. The given delay may be of 500 ns, 250 ns, 100ns, 50 ns, 25 ns, 10 ns, 5 ns, etc.

The high voltage pulser 105 may include, for example, a plurality ofsolid state switches (e.g., IGBT, MOSFET, FETs, SiC, GAN switches)and/or a transformer. The high voltage pulser 105 may, for example, bedesigned and/or constructed with low stray inductance and/or low straycapacitance. The high voltage pulser 105 may, for example, may producehigh voltage pulses having a fast rise time, a high voltage (e.g.,greater than 1 kV), a variable pulse width, a high repetition rate, etc.Any type of high voltage pulser may be used. The high voltage pulser 105may include the high voltage nanosecond pulser described in U.S. PatentPublication 2015/0130525 and/or U.S. Patent Publication 2015/0318846 theentirety of each of which are incorporated by reference for disclosing apulser 105.

In some embodiments, the high voltage pulser 105 may, for example,operate with variable pulse widths, voltages greater than 1 kV (or evenup to 100 kV), and/or a pulse repetition frequency of 10 kHz-100 kHz.

In some embodiments, the high voltage pulser 105 may operate in a singlepulse regime, or in a regime with long pulses.

In some embodiments, the pulse recirculating circuit 125 can beelectrically coupled with the load 120 and the input of the nonlineartransmission line 115. The pulse recirculating circuit 125 canrecirculate pulses from the load 120 to the input of the nonlineartransmission line 115 with a given delay.

In some embodiments, the pulse recirculating circuit 125 can beelectrically coupled with the load 120 and the output of the nonlineartransmission line 115. The pulse recirculating circuit 125 canrecirculate pulses from the load 120 to the output of the nonlineartransmission line 115 with a given delay.

In some embodiments, the pulse recirculating circuit 125 can beelectrically coupled with the load 120 and the input of the load 120.The pulse recirculating circuit 125 can recirculate pulses from the load120 to the input of the load 120 with a given delay.

In some embodiments, the pulse recirculating circuit 125 can beelectrically coupled with a portion of the of the nonlinear transmissionline. For example, a nonlinear transmission line may have a firstplurality of lumped elements arranged in series with a second pluralityof lumped elements. The pulse recirculation circuit 125 may be coupledat with the nonlinear transmission line at position between the firstplurality of the lumped elements and the second plurality of lumpedelements. As another example, the pulse recirculating circuit may beelectrically coupled with a portion of a gyromagnetic nonlineartransmission line.

In some embodiments, the pulser 105 may inject a high voltage pulse witha given amount of energy into the nonlinear transmission line 115. Someenergy from this high voltage pulse may be dissipated by the nonlineartransmission line 115. When the pulse reaches the antenna (e.g., load120), some of this energy may be radiated away as electromagneticradiation. The energy from the pulse that was not radiated, can enterthe pulse recirculating circuit 125. Some of the pulse energy may bedissipated by losses in the recirculating circuit 125. In someembodiments, the recirculated pulse can reenter the nonlineartransmission line 115, where some energy may be dissipated due tolosses. Energy in the recirculated pulse can be radiated from theantenna, and the remaining energy may enter the recirculating circuit.This may be repeated until there is no more energy in that pulse and/orthe voltage is too small to be useful.

For example, if a high voltage pulse from the pulser is 20 kV and is 100ns wide, and the nonlinear transmission line 115 and/or the antenna are50 Ohms, the pulse energy can be calculated as follows:

$E = {{\frac{V^{2}}{Z}\Delta t} = {{\frac{\left( {20{kV}} \right)^{2}}{50\Omega}\left( {100{ns}} \right)} = {800mJ}}}$

Assuming, for example, the nonlinear transmission line 115 is 96%efficient, the antenna radiates 10% of the pulse energy, and therecirculating circuit 125 is 98% efficient. The following table showsthe energy in millijoules (mJ) when the pulse is at different locationsin the circuit for a single pulse.

Energy Energy into Energy out of Pass NLTL NLTL Radiated byRecirculating Recirculating Number Input Output Antenna Circuit circuit1 800.0 768.0 76.8 691.2 677.4 2 677.4 650.3 65.0 585.3 573.5 3 573.5550.6 55.1 495.5 485.6 4 485.6 466.2 46.6 419.6 411.2 5 411.2 394.7 39.5355.3 348.2 6 348.2 334.2 33.4 300.8 294.8 7 294.8 283.0 28.3 254.7249.6 8 249.6 239.6 24.0 215.7 211.4

In some embodiments, when the pulse reaches the end of the recirculatingcircuit 125 and/or the nonlinear transmission line 115 input, a secondpulse may be produced by the pulser 105, which combines with therecirculating pulse. The pulser 105 may add additional energy to therecirculating pulse. This process may be repeated so that the pulsenever decays significantly.

In some embodiments, the pulser may add energy at alternaterecirculating pulses such as, for example, the 2^(nd), 3^(rd) . . . orn^(th) pass through the recirculating circuit.

FIG. 2 is a block diagram of a high frequency electromagnetic radiationgeneration device 200 having a pulse recirculating circuit according tosome embodiments. In some embodiments, the pulse recirculating circuitmay include a filter 205, a diode 210, and/or a transmission line 215.The filter 205, for example, may include any type of filter that canensure RF frequencies are being sent to the load 120. As an example, thefilter 205 can include a capacitor and/or an inductor. The filter 205,for example, can include any type of low pass filter such as, forexample, an LC, RC, RL, and/or RLC filter. As another example, a higherorder filter may also be used.

The transmission line 215 may include a delay line that can be used toset the delay time between pulses. The transmission line 215 may providea delay, for example, that is consistent with delay between pulsesprovided by the pulser 105. The transmission line 215 may includetunable switches, inductors, capacitors, resistors, etc. In someembodiments, the transmission line 215 can include a length ofconducting material (e.g., a wire or cable) where the length of thetransmission line and/or the type of conducting material can set theamount delay introduced by the transmission line. In some embodiments,the delay, t_(delay), introduced by the transmission line 215 may be adetermined from the pulse repetition frequency, PRF_(pulser), of thenanosecond pulser 105 and the number of times, N, the pulse went throughthe recirculating circuit between the pulses from the pulser 105, suchas, for example:

${N\left( {t_{delay} + t_{NLTL}} \right)} = {\frac{1}{PRF_{pulser}}.}$

In addition, the pulse repetition frequency of the electromagneticradiation, PRF_(RF), is:

PRF _(RF) =PRF _(pulser) *N.

In some embodiments, the pulser 105 may provide an initial pulse havingan initial voltage with an initial current draw providing an initialenergy to the nonlinear transmission line. The pulser may providesubsequent pulses that have the same voltage, but provide a lowercurrent draw and, therefore, a lower energy to the nonlineartransmission line. The subsequent pulses may be combined withrecirculated pulses. For example, each subsequent pulse may be combinedwith a recirculated pulse at the input of the nonlinear transmissionline 115. In some embodiments, the subsequent pulses may have a voltagethat is 20%, 30%, 40%, 50% or 60% of the initial energy. In someembodiments, after a given number of subsequent pulses (e.g., 5, 10, 20,etc. pulses) another pulse may be provided that has the initial voltage.

FIG. 3 is a circuit diagram of a nonlinear transmission line with apulse recirculating circuit according to some embodiments. In thisexample, the pulse recirculating circuit includes a filter comprisingcapacitor C101 and inductor L201. The transmission line W1 controls thedelay in pulses. In this example, two diodes are shown. Diode D3 ispositioned near the load R81. Diode D1 may, for example, be positionednear the input of the nonlinear transmission line. Diode D2 may, forexample, be placed between the pulser and the nonlinear transmissionline.

FIG. 4 is an example flow chart of a process 400 for radiatingelectromagnetic pulses using a pulser with a pulse recirculating circuitaccording to some embodiments. Process 400 starts at block 405. At block410, a high voltage nanosecond pulse may be generated. The high voltagenanosecond pulse, for example, may be generated by pulser 105. The highvoltage nanosecond pulse, for example, may have a rise time less thanabout 50 ns, ns, 30 ns, 20 ns, 10 ns, etc. The high voltage nanosecondpulse, for example, may have a pulse width less than about 100 ns, 50ns, 25 ns, 10 ns, 5 ns, etc. The high voltage nanosecond pulse, forexample, may have voltage greater than 5 kV, 10 kV, 20 kV, etc.

At block 415 electromagnetic radiation may generated from the highvoltage nanosecond pulse. The electromagnetic radiation, for example,may radiate from an antenna at a frequency greater than 100 MHz. In someembodiments, only a portion of the energy from the high voltagenanosecond pulse may be converted to electromagnetic radiation.

At block 420, it can be determined if the number of recirculated pulsesis lower than the desired number of recirculated pulses, N, then process400 proceeds to block 425. Additionally or alternatively, at block 420it can be determined whether voltage of the pulse from the nonlineartransmission line is less than a threshold voltage.

At block 425, the portion of the high voltage nanosecond pulse notconverted to electromagnetic radiation may be recirculated through aportion of the circuitry with a delay t. In some embodiments, a portionof the high voltage nanosecond pulse not converted to electromagneticradiation may be recirculated regardless of the number of recirculatedpulses.

If the number of recirculated pulses is equal to or lower than thedesired number of recirculated pulses, N, then process 400 proceeds toblock 430. At block 430, if the pulsing and creation of electromagneticradiation is to continue, then process 400 returns to block 410 andanother high voltage nanosecond pulse is generated. Thus, using process400, a single high voltage nanosecond pulse generated at block 410 canproduce N electromagnetic pulses.

If the pulsing is complete, as determined at block 430, then process 400proceeds to block 435, where process 400 ends.

FIG. 5 is an example flow chart of a process 500 for radiatingelectromagnetic pulses using a pulser with a pulse recirculating circuitaccording to some embodiments. Process 500 starts at block 505. At block510, a first high voltage nanosecond pulse may be generated. The firsthigh voltage nanosecond pulse, for example, may be generated by pulser105. The first high voltage nanosecond pulse, for example, may have arise time less than about 50 ns, 40 ns, 30 ns, 20 ns, 10 ns, etc. Thefirst high voltage nanosecond pulse, for example, may have a pulse widthless than about 100 ns, 50 ns, 25 ns, 10 ns, 5 ns, etc. The first highvoltage nanosecond pulse, for example, may have voltage greater than 5kV, 10 kV, etc.

At block 515 electromagnetic radiation may generated from the first highvoltage nanosecond pulse. The electromagnetic radiation, for example,may radiate from an antenna at a frequency greater than 100 MHz. In someembodiments, only a portion of the energy from the high voltagenanosecond pulse may be converted to electromagnetic radiation.

At block 520 a portion of the portion of the first high voltagenanosecond pulse not converted to electromagnetic radiation may berecirculated through a portion of the circuitry with a delay t. Forexample, the portion of the first high voltage nanosecond pulse notconverted to electromagnetic radiation may be recirculated through therecirculating circuit 125.

At block 525 a subsequent high voltage nanosecond pulse may begenerated. The subsequent high voltage nanosecond pulse, for example,may be generated by pulser 105. The subsequent high voltage nanosecondpulse, for example, may have a rise time less than about ns, 40 ns, 30ns, 20 ns, 10 ns, etc. The subsequent high voltage nanosecond pulse, forexample, may have a pulse width less than about 100 ns, 50 ns, 25 ns, 10ns, 5 ns, etc. The subsequent high voltage nanosecond pulse, forexample, may have voltage greater than 5 kV, kV, 20 kV, etc. In someembodiments, the subsequent high voltage nanosecond pulse may have avoltage substantially equal to the first high voltage nanosecond pulse.

In some embodiments, the subsequent high voltage nanosecond pulse maydraw a current that is less than the current drawn by the first highvoltage nanosecond pulse. In some embodiments, the subsequent highvoltage nanosecond pulse may have a power less than the power of thefirst high voltage nanosecond pulse.

In some embodiments, the subsequent high voltage nanosecond pulse mayhave a current draw and/or power that varies based on the current and/orpower of the recirculated pulse.

At block 530, the subsequent high voltage nanosecond pulse and therecirculated pulse can be combined. This combination can occur, forexample, by timing the recirculated pulse with the timing of thesubsequent high voltage nanosecond pulse.

At block 535, electromagnetic radiation may be generated from thecombined pulse. The electromagnetic radiation, for example, may radiatefrom an antenna at a frequency greater than 100 MHz. In someembodiments, only a portion of the energy from the high voltagenanosecond pulse may be converted to electromagnetic radiation.

At block 540, if the pulsing and creation of electromagnetic radiationis to continue, then process 500 proceeds to block 545, otherwiseprocess 500 proceeds to block 550 and process 500 ends. At block 540 itmay be determined to discontinue pulsing if the voltage of the combinedpulse is below a threshold.

At block 545, a portion of the portion of the combined pulse notconverted to electromagnetic radiation may be recirculated through aportion of the circuitry with a delay t. For example, the portion of thecombined pulse not converted to electromagnetic radiation may berecirculated through the recirculating circuit 125. Process 500 mayproceed to block 525.

Blocks 525, 530, 535, 540, and 545 of process 500 may repeat for anynumber of cycles.

In some embodiments, if the voltage of a recirculated pulse drops belowa threshold value, then process 500 may proceed to block 510.

FIG. 6 is a diagram showing the output at the load and the output at thenonlinear transmission line according to some embodiments. As shown, thehigh voltage output of the nonlinear transmission line is initially asquare wave pulse provided by the pulser 105 and travels through thenonlinear transmission line 115. Later the high voltage pulses can bepulses recirculated from the output of the nonlinear transmission lineusing the pulse recirculating circuit 125. These high voltage pulses cancreate discrete electromagnetic pulses. In this example, the discreteelectromagnetic pulses can be about 50 ns in length. In this example, asingle high voltage pulse from the pulser 105 can produce a plurality ofelectromagnetic pulses every 500 ns. The first pulse can be provideddirectly from the pulser and the other high voltage pulses can beprovided by the pulse recirculating circuit 125.

FIG. 7 is a diagram showing energy efficiency versus time using pulserecirculating according to some embodiments. Here it can be seen thatrather than lose the majority of the energy in the broad band pulse thepulse can be reutilized (or recirculated) to increase the overallefficiency of the system. In some embodiments, efficiencies greater than20%, 30%, 40% or 50% can be achieved,

FIG. 8 is a diagram showing a pulse measured across a load and the pulsemeasured across a load inside the pulse recirculating circuit accordingto some embodiments.

FIG. 9 is a diagram showing a pulse being extinguished over timeaccording to some embodiments.

In some embodiments, a nonlinear transmission line may include aplurality of nonlinear semiconductor junction capacitance devices (e.g.,nonlinear capacitors). In some embodiments, the nonlinear transmissionline may sharpen the rise time of a high voltage input pulse that may,for example, have a variable pulse width and/or a high pulse repetitionrate. In some embodiments, the rise time of the input pulse becomesharper and sharper as it propagates through the elements of thenonlinear transmission line the output may begin to ring producing ahigh frequency electromagnetic pulse.

Some embodiments of the invention include the use of a nonlinearsemiconductor junction capacitance device as part of the nonlineartransmission line. A nonlinear semiconductor junction capacitance devicein some voltage regimes may have a capacitance that varies as voltageacross the nonlinear semiconductor junction capacitance device.

A nonlinear semiconductor junction can include a P-type or an N-typejunction. A semiconductor junction defined by the boundary betweenregions of P-type and N-type conductivity material is a capacitor undercertain conditions. This junction capacitance arises from the electricalcharge of the depletion layer or space-charge region associated with thejunction. The space-charge region identifies a volume adjoining thejunction on both sides within which the net fixed charge arising fromthe presence of ionized impurity atoms is not neutralized by mobilecharge carriers. Outside of the depletion layer the mobile carriers,holes in the P-type material and electrons in the N-type, are present inalmost exactly the right numbers to neutralize the fixed charges.

If the junction is biased slightly in the forward or reverse directionby applying a voltage to a contact on one side of the junction, thisvoltage urges the hole and electron distributions to move toward or awayfrom each other, respectively. Additional holes and electrons enter orleave the semiconductor at the contacts to maintain the neutrality ofthe P-type and N-type regions as the depletion layer narrows or widens.Therefore, a certain amount of charge is introduced at the terminals ofthe device and, neglecting recombination or generation of chargecarriers, the same amount of charge returns if the applied voltage ischanged back to zero. Thus, the semiconductor junction device is like acapacitor. The relation between the applied voltage and the amount ofcharge introduced at the terminals is nonlinear; i.e. the capacitance,defined as the rate of change of charge as voltage is changed, dependsupon the voltage.

A nonlinear semiconductor junction can also include ametal-semiconductor junction in which a metal is in close contact with asemiconductor material. This close contact between the metal and thesemiconductor material can create a junction capacitance that may varywith applied voltage. A metal-semiconductor junction can be referred toas a Schottky barrier diode, Schottky barrier junction, or a pointcontact diode. A metal-semiconductor junction may include, for example,a metal with either a P-type or an N-type semiconductor region.

In some embodiments, a NSJC device may be a capacitor or a number ofplurality of capacitors. In some embodiments, a NSJC device may includetwo parallel conductors (or a capacitor) etched on a circuit board.

A nonlinear transmission line may include a plurality of circuitelements that each include at least one inductor and at least one NSJCdevice such as, for example, a capacitor. The speed at which the inputpulse propagates the nonlinear transmission line changes as a functionof voltage. Thus, the high voltage components of the input pulsepropagate down the line faster than the slow voltage components of theinput pulse. This can lead to a sharpening of the rising edge of thepulse as it propagates down the line. Each element changes the rise timeby approximately:

Δt _(element)˜√{square root over (LC(V _(10%)))}−√{square root over(LC(V _(90%)))}.

The nonlinear transmission line may sharpen the rising edge of an inputpulse sufficiently that a shock at the output from the nonlineartransmission line may form and the output begins to ring producing ahigh frequency output signal.

FIG. 18 is a circuit diagram of a nonlinear transmission line 1000according to some embodiments. The nonlinear transmission line 1000 mayinclude an input that can connect to a high voltage pulser 105. In someembodiments, a high voltage pulser may include the nonlineartransmission line 1000.

The nonlinear transmission line 1000 includes a first circuit element250A that includes a first NSJC device 240A and a first inductor 220A.The first circuit element 250A may be electrically coupled to both thehigh voltage pulser 105 and ground.

The nonlinear transmission line 1000 includes a second circuit element250B that includes a second NSJC device 240B and a second inductor 220B.The second circuit element 250B may be electrically coupled to both thefirst inductor 220A and ground.

The nonlinear transmission line 1000 includes a third circuit element250C that includes a third NSJC device 240C and a third inductor 220C.The third circuit element 250C may be electrically coupled to both thesecond inductor 220B and ground.

The nonlinear transmission line 1000 includes a fourth circuit element250D that includes a fourth NSJC device 240D and a fourth inductor 220D.The fourth circuit element 250D may be electrically coupled to both thethird inductor 220C and ground.

The nonlinear transmission line 1000 may include an output that isconnected with an antenna that can radiate a high voltage microwavesignal.

The nonlinear transmission line 1000 shown in FIG. 18 shows four circuitelements (each having an inductor and an NSJC device). Any number ofcircuit elements and/or inductors may be included. For example, anonlinear transmission line may include ten or more circuit elementsand/or inductors. As another example, a nonlinear transmission line mayinclude forty or more circuit elements and/or inductors.

In some embodiments, each NSJC device (e.g., NSJC device 240A, 210B,210C, 210D, etc.) may have an inductance or a stray inductance less thanabout 500 nH, 250 nH, 100 nH. 50 nH, 25 nH, etc. In some embodiments,each NSJC device (e.g., NSJC device 240A, 210B, 210C, 210D, etc.) mayinclude a plurality of NSJC device in series or parallel.

In some embodiments, each NSJC device (e.g., NSJC device 240A, 210B,210C, 210D, etc.) may have a zero-voltage capacitance (e.g., thecapacitance measured when no voltage is applied to the NSJC device) lessthan about 10 nH, 1 nH, 500 pH, 250 pH, 100 ph. 50 pH, 25 pH, etc.

In some embodiments, each inductor (e.g., inductor 220A, 240B, 240C,240D, etc.) may have an inductance less than about 500 nH, 250 nH, 100nH. 50 nH, 25 nH, etc. In some embodiments, each inductor (e.g.,inductor 220A, 240B, 240C, 240D, etc.) may include a plurality ofinductors arranged in series or parallel.

FIG. 3 is a circuit diagram of a nonlinear transmission line 1100according to some embodiments. The circuit diagram of the nonlineartransmission line 1100 shows a number of stray elements such as strayresistance represented as a resistor and stray inductance represented asan inductor.

The nonlinear transmission line 1100 includes a first circuit element250A that includes a first NSJC device 240A and first inductor 220A. Thefirst circuit element 250A may also include stray inductance, which isschematically represented by inductor 205A. In some embodiments, thestray inductance represented by inductor 205A can represent all or mostof the stray inductance of the first circuit element 250A, such as, forexample, the inductance of traces in the circuit element, inductance ofthe NSJC device, etc. The first circuit element 250A may also includestray resistance, which can be schematically represented by resistors210A and 225A. In some embodiments, the stray resistance represented byresistors 210A and 225A can represent all or most of the strayresistance of the first circuit element 250A such as, for example, theresistance of traces in the circuit element, resistance of the NSJCdevice, etc.

The nonlinear transmission line 1100 includes a second circuit element250B that includes a second NSJC device 240B and second inductor 220B.The second circuit element 250B may also include stray inductance, whichis schematically represented by inductor 205B. In some embodiments, thestray inductance represented by inductor 205B can represent all or mostof the stray inductance of the second circuit element 250B, such as, forexample, the inductance of traces in the circuit element, inductance ofthe NSJC device, etc. The second circuit element 250B may also includestray resistance, which can be schematically represented by resistors210B and 225B. In some embodiments, the stray resistance represented byresistors 210B and 225B can represent all or most of the strayresistance of the second circuit element 250B.

The nonlinear transmission line 1100 includes a third circuit element250C that includes a third NSJC device 240C and third inductor 220C. Thethird circuit element 250C may also include stray inductance, which isschematically represented by inductor 205C. In some embodiments, thestray inductance represented by inductor 205C can represent all or mostof the stray inductance of the third circuit element 250C, such as, forexample, the inductance of traces in the circuit element, inductance ofthe NSJC device, etc. The third circuit element 250C may also includestray resistance, which can be schematically represented by resistors210C and 225C. In some embodiments, the stray resistance represented byresistors 210C and 225C can represent all or most of the strayresistance of the third circuit element 250C such as, for example, theresistance of traces in the circuit element, resistance of the NSJCdevice, etc.

The nonlinear transmission line 1100 includes a fourth circuit element250D that includes a fourth NSJC device 240D and fourth inductor 220D.The fourth circuit element 250D may also include stray inductance, whichis schematically represented by inductor 205D. In some embodiments, thestray inductance represented by inductor 205D can represent all or mostof the stray inductance of the fourth circuit element 250D, such as, forexample, the inductance of traces in the circuit element, inductance ofthe NSJC device, etc. The fourth circuit element 250D may also includestray resistance, which can be schematically represented by resistors210D and 225D. In some embodiments, the stray resistance represented byresistors 210D and 225D can represent all or most of the strayresistance of the fourth circuit element 250D such as, for example, theresistance of traces in the circuit element, resistance of the NSJCdevice, etc.

In some embodiments, each one of the plurality of inductors 220A, 220B,220C, 220D may have a value greater than a respective stray inductancerepresented by each or any one of inductors 205A, 205B, 205C, 205D.

In some embodiments, the stray resistance represented by resistors 210A,210B, 210C, 210D may have a resistance less than about 5.0, 2.5, 1.0,0.5, etc. ohms. In some embodiments, the stray resistance represented byresistors 210A, 210B, 210C, 210D may be minimized. In some embodiments,the stray resistance represented by resistors 210A, 210B, 210C, 210D mayinclude, for example, the internal resistance of the NSJC device and/orany of its connections. In some embodiments, the stray resistancerepresented by resistors 210A, 210B, 210C, 210D may comprise theresistance of a wire, a trace, a plurality of wires, a plurality oftraces, litz wire, etc.

In some embodiments, the stray resistance represented by resistors 225A,225B, 225C, 225D may be as small as possible. In some embodiments, thestray resistance represented by resistors 225A, 225B, 225C, 225D may beas minimized. In some embodiments, the stray resistance represented byresistors 225A, 225B, 225C, 225D may comprise the resistance of a wire,a trace, a plurality of wires, a plurality of traces, litz wire, etc.

While the transmission line 1100 shown in FIG. 3 shows four circuitelements any number of circuit elements may be used. In someembodiments, each NSJC device 240A, 240B, 240C, or 240D may include oneor more NSJC devices in series or parallel (e.g., 2, 3, 5, 7, 9, 12, 15diodes arranged in series), which may, for example, provide for a NSJCdevice combination with sufficient operating voltage such as, forexample, a combined operating voltage greater than 500 V, 1 kV, 2.5 kV,5 kV, 10 kV, etc. In some embodiments, each NSJC device 240A, 240B,240C, or 240D may comprise one or more Schottky diode such as, forexample, silicon carbide Schottky diode(s), silicon diodes, or otherdevices such as, for example, a solid-state switch, FET, MOSFET, IGBT,GAN, SiC, MOSFET, etc.

Each NSJC device 240A, 240B, 240C, or 240D (or combination of diodes),for example, may have a voltage ratings of more than 1.0 kV such as, forexample, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 3.4kV. In some embodiments, each NSJC device 240A, 240B, 240C, or 240D (orcombination of diodes) may have a respective stray inductance 205A,205B, 205C, 205D less than about 1,000 nH, 750 nH, 500 nH, 250 nH, 100nH, 50 nH, 30 nH, 20 nH, 15 nH, 10 nH, etc.

While the nonlinear transmission line 1100 shown in FIG. 3 shows fourinductors 220A, 220B, 220C, 220D any number of inductors may be used.The inductors, for example, may have an inductance less than about 250nH, 100 nH, 50 nH, 25 nH, 10 nH, etc.

In some embodiments, the nonlinear transmission line 1100 may be coupledwith a nanosecond pulser that can produce a high voltage pulse trainwith a plurality of pulses. The high voltage pulse train produced by thenanosecond pulser may have any number of characteristics such as, forexample, having a voltage such as, for example, above 1 kV, 2.5 kV, 5kV, 10 kV, 15 kV, 20 kV, etc.; and a fast rise time such as, forexample, a rise time less than about 50 ns, 40 ns, 30 ns, 20 ns, 10 ns,etc., etc. The plurality of pulses of the high voltage pulse train may,for example, have variable pulse widths (e.g., 3-275 ns).

FIG. 12 is a circuit diagram of a nonlinear transmission line 1200according to some embodiments. The circuit diagram of the nonlineartransmission line 1200 shows a number of stray elements such as strayresistance represented as a resistor and stray inductance represented asan inductor. In addition, the circuit diagram of the nonlineartransmission line 1200 includes two inductors within each circuitelement.

In some embodiments, the nonlinear transmission line 1200 may include aplurality circuit elements that each include a NSJC device. In thisexample, each circuit element includes two inductors.

The nonlinear transmission line 1200 includes a first circuit element250A that includes a first NSJC device 240A, a first lower inductor220A, and a first upper inductor 221A. The first circuit element 250Amay also include stray inductance, which is schematically represented byinductor 205A. In some embodiments, the stray inductance represented byinductor 205A can represent all or most of the stray inductance of thefirst circuit element 250A, such as, for example, the inductance oftraces in the circuit element, inductance of the NSJC device, etc. Thefirst circuit element 250A may also include stray resistance, which canbe schematically represented by resistors 210A, 225A, and 226A. In someembodiments, the stray resistance represented by resistors 210A, 225A,and 226A can represent all or most of the stray resistance of the firstcircuit element 250A such as, for example, the resistance of traces inthe circuit element, resistance of the NSJC device, etc.

The nonlinear transmission line 1200 includes a second circuit element250B that includes a second NSJC device 240B, second lower inductor220B, and second upper inductor 221B. The second circuit element 250Bmay also include stray inductance, which is schematically represented byinductor 205B. In some embodiments, the stray inductance represented byinductor 205B can represent all or most of the stray inductance of thesecond circuit element 250B, such as, for example, the inductance oftraces in the circuit element, inductance of the NSJC device, etc. Thesecond circuit element 250B may also include stray resistance, which canbe schematically represented by resistors 210B, 225B, and 226B. In someembodiments, the stray resistance represented by resistors 210B, 225B,and 226B can represent all or most of the stray resistance of the secondcircuit element 250B such as, for example, the resistance of traces inthe circuit element, resistance of the NSJC device, etc.

The nonlinear transmission line 1200 includes a third circuit element250C that includes a third NSJC device 240C, third lower inductor 220C,and third upper inductor 221C. The third circuit element 250C may alsoinclude stray inductance, which is schematically represented by inductor205C. In some embodiments, the stray inductance represented by inductor205C can represent all or most of the stray inductance of the thirdcircuit element 250C, such as, for example, the inductance of traces inthe circuit element, inductance of the NSJC device, etc. The thirdcircuit element 250C may also include stray resistance, which can beschematically represented by resistors 210C, 225C, and 226C. In someembodiments, the stray resistance represented by resistors 210C, 225C,and 226C can represent all or most of the stray resistance of the thirdcircuit element 250C such as, for example, the resistance of traces inthe circuit element, resistance of the NSJC device, etc.

The nonlinear transmission line 1200 includes a fourth circuit element250D that includes a fourth NSJC device 240D, fourth lower inductor220D, and fourth upper inductor 221D. The fourth circuit element 250Dmay also include stray inductance, which is schematically represented byinductor 205D. In some embodiments, the stray inductance represented byinductor 205D can represent all or most of the stray inductance of thefourth circuit element 250D, such as, for example, the inductance oftraces in the circuit element, inductance of the NSJC device, etc. Thefourth circuit element 250D may also include stray resistance, which canbe schematically represented by resistors 210A, 225D, and 226D. In someembodiments, the stray resistance represented by resistors 210D, 225D,and 226D can represent all or most of the stray resistance of the fourthcircuit element 250D such as, for example, the resistance of traces inthe circuit element, resistance of the NSJC device, etc.

In some embodiments, an inductor pair, for example, inductor pairs 220Aand 221A, 220B and 221B, 220C and 221C, 220D and 221D may beelectrically coupled between two circuit elements and/or a circuitelement and an output. In some embodiments, each one of the plurality ofinductors 220A, 220B, 220C, 220D, 221A, 221B, 221C, 221D, may have avalue greater than a respective stray inductance represented by one ofinductors 205A, 205B, 205C, 205D.

In some embodiments, the stray resistance represented by resistors 210A,210B, 210C, 210D may have a resistance less than about 5.0, 2.5, 1.0,0.5, etc. ohms. In some embodiments, the stray resistance represented byresistors 210A, 210B, 210C, 210D may be minimized. In some embodiments,the stray resistance represented by resistors 210A, 210B, 210C, 210D maycomprise the resistance of a wire, a trace, a plurality of wires, aplurality of traces, litz wire, etc.

While the transmission line 1200 shown in FIG. 12 shows four circuitelements any number of circuit elements may be used. In someembodiments, each NSJC device 240A, 240B, 240C, 240D may include one ormore NSJC devices in series or parallel (e.g., 2, 3, 5, 7, 9, 12, 15diodes arranged in series), which may, for example, provide for a NSJCdevice combination with sufficient operating voltage such as, forexample, a combined operating voltage greater than 500 V, 1 kV, 2.5 kV,5 kV, 10 kV, etc. In some embodiments, each NSJC device 240A, 240B,240C, or 240D may comprise one or more Schottky diode such as, forexample, silicon carbide Schottky diode(s), silicon diodes, or other.

In some embodiments, each NSJC device 240A, 240B, 240C, or 240D (orcombination of diodes), for example, may have a voltage ratings of morethan 1.0 kV such as, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.8,1.9, 2.0, 2.1, 2.2, 2.3, 3.4 kV. In some embodiments, each NSJC device240A, 240B, 240C, or 240D (or combination of diodes) may have arespective stray inductance 205A, 205B, 205C, 205D less than about 1,000nH, 750 nH, 500 nH, 250 nH, 100 nH, 50 nH, 30 nH, 20 nH, 15 nH, 10 nH,etc.

While the nonlinear transmission line 1200 shown in FIG. 12 shows fourinductor pairs 220A and 221A, 220B and 221B, 220C and 221C, 220D and221D any number of inductors may be used. The inductors 220A, 220B,220C, 220D, for example, may have an inductance less than about 250 nH,100 nH, 50 nH, 25 nH, 10 nH, etc.

In some embodiments, the nonlinear transmission line 1200 may be coupledwith a nanosecond pulser that can produce a high voltage pulse trainwith a plurality of pulses. The high voltage pulse train produced by thenanosecond pulser may have any number of characteristics such as, forexample, having a voltage such as, for example, above 1 kV, 2.5 kV, 5kV, 10 kV, 15 kV, 20 kV, etc.; and a fast rise time such as, forexample, a rise time less than about 50 ns, 40 ns, 30 ns, 20 ns, 10 ns,etc., etc. The plurality of pulses of the high voltage pulse train may,for example, have variable pulse widths (e.g., 3-275 ns).

In some embodiments, a nonlinear transmission line can include a NSJCdevice that has the following capacitance:

$\begin{matrix}{{C(V)} = {\frac{C_{j0}}{\left( {1 + {V/\phi}} \right)^{m}}.}} & (V)\end{matrix}$

Where C_(j0) is the junction capacitance of the NSJC at zero voltage. Vis the voltage. φ is the junction potential. m is a constant valuebetween 0.25 and 0.75 that varies based on the type of NSJC.

The following table provides some example values for a nonlineartransmission line that can be used to create high voltage microwavepulses at various frequencies. In some embodiments, each value may rangefrom the 25% below the listed LF value to 25% above the listed HF value.

Variable Description LF Value HF Value C_(j0) Junction capacitance1.3856 nF 173.2 pF at zero voltage φ  1.75 V 1.75 V m For a siliconcarbide (SiC) device 0.5 0.5 L_(stray) Stray inductance (205.) 100 pH 100 pH   L Inductance (220.)  48 nH   6 nH R_(L) Stray resistance in 100mΩ 10 mΩ inductor leg (225) R_(C) Stray resistance in 100 mΩ 10 mΩcapacitor leg (210) N Number of elements 30   140    f_(RF) Measured RFfrequency  325 MHz  2.4 GHz ω_(RF) RF angular frequency  2.0 × 10⁹ s⁻¹15.1 × 10⁹ s⁻¹ ω_(Bragg) Bragg cutoff frequency 2.13 × 10⁹ s⁻¹ 17.1 ×10⁹ s⁻¹

FIG. 13 is a circuit diagram a nonlinear transmission line 1300 with 30circuit elements according to some embodiments. FIG. 14 is a diagram ofan input pulse 605 from a high voltage pulser 105 and an output pulse610 after propagating through the nonlinear transmission line 1300 shownin FIG. 13 . As shown in the diagram, the input pulse 605 is 20 kV pulsewith a 60 ns flat top and a rise time of 10 ns. The output pulse is ahigh voltage signal with a frequency of 325 MHz. The various elements inthe nonlinear transmission line 1300 may have the LF Values listed inthe table above.

FIG. 15 is a circuit diagram a nonlinear transmission line with 140circuit elements according to some embodiments. FIG. 16 is a diagram ofan input pulse 805 from a high voltage pulser 105 and an output pulse810 after propagating through the nonlinear transmission line shown inFIG. 15 . As shown in the diagram, the input pulse 805 is 20 kV pulsewith a 60 ns flat top and a rise time of 10 ns. The output pulse is ahigh voltage signal with a frequency of 2.4 GHz. The various elements inthe nonlinear transmission line in FIG. 15 may have the HF Values listedin the table above.

FIG. 13 and FIG. 15 illustrate two examples of nonlinear transmissionlines have various component values. These values may vary based onimplantation and/or design.

In some embodiments, a nonlinear transmission line can include a NSJCdevice (e.g., a Schottky diode) that has the following capacitance:

$C_{s} = {\frac{1}{n}\frac{C_{j0}}{\sqrt{1 + {{V_{s}/n}\varphi}}}}$

In some embodiments, the overall capacitance, C_(s), of the nonlineartransmission line will decrease with increased number of diode (or NSJCdevice) sections n. C_(j0) is the junction capacitance at zero voltageof a single diode, φ is the junction potential and V_(s) is the voltageacross the nonlinear transmission line.

In some embodiments, as a general rule of thumb, in some conditions, thecharacteristic impedance of a nonlinear transmission line may be lessthan about 180 ohms. In some embodiments, the inductance of thenonlinear transmission line can be calculated, for example, to impedancematch to 180Ω using the following formula, where V₄₀% is 40% of V_(max):

$Z = {\sqrt{\frac{L}{C\left( V_{40\%} \right)}}.}$

In some embodiments, the impedance of the nonlinear transmission linemay vary as a function of the voltage applied and/or, for example, time,as the input pulse is applied.

FIG. 17 is a diagram of an input pulse from a high voltage pulser and anoutput pulse after propagating through the nonlinear transmission lineaccording to some embodiments. FIG. 18 is a zoomed in portion of thediagram shown in FIG. 17 . In this example, the input pulse has a fastrise time (e.g., ˜12.5 ns) and the output pulse has a faster front endrise time (e.g., ˜1.2 ns). In this example, the output pulse has afrequency of 323 MHz oscillating at 6 kV.

The term “substantially” means within 5% or 10% of the value referred toor within manufacturing tolerances.

Various embodiments are disclosed. The various embodiments may bepartially or completely combined to produce other embodiments.

Numerous specific details are set forth herein to provide a thoroughunderstanding of the claimed subject matter. However, those skilled inthe art will understand that the claimed subject matter may be practicedwithout these specific details. In other instances, methods,apparatuses, or systems that would be known by one of ordinary skillhave not been described in detail so as not to obscure claimed subjectmatter.

The use of “adapted to” or “configured to” herein is meant as open andinclusive language that does not foreclose devices adapted to orconfigured to perform additional tasks or steps. Additionally, the useof “based on” is meant to be open and inclusive, in that a process,step, calculation, or other action “based on” one or more recitedconditions or values may, in practice, be based on additional conditionsor values beyond those recited. Headings, lists, and numbering includedherein are for ease of explanation only and are not meant to belimiting.

While the present subject matter has been described in detail withrespect to specific embodiments thereof, it will be appreciated thatthose skilled in the art, upon attaining an understanding of theforegoing, may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, it should be understoodthat the present disclosure has been presented for-purposes of examplerather than limitation, and does not preclude inclusion of suchmodifications, variations, and/or additions to the present subjectmatter as would be readily apparent to one of ordinary skill in the art.

That which is claimed is:
 1. A high frequency electromagnetic radiationgeneration device comprising: a high voltage input configured to receiveelectrical pulses having a first peak voltage that is greater than 5 kV;a nonlinear transmission line electrically coupled with the high voltageinput; an antenna electrically coupled with the nonlinear transmissionline that radiates electromagnetic radiation at a frequency greater than100 MHz about a voltage greater than 5 kV; and a pulse recirculatingcircuit electrically coupled with the high voltage input and theantenna, the pulse recirculating circuit comprising: a diode; a low passfilter; and a delay line; wherein unradiated energy from the antenna isdirected through the pulse recirculating circuit to the nonlineartransmission line with a delay of less than 500 ns.
 2. The highfrequency electromagnetic radiation generation device according to claim1, wherein the nonlinear transmission line comprises a plurality ofcircuit elements that include a nonlinear semiconductor junctioncapacitance device and an inductor.
 3. The high frequencyelectromagnetic radiation generation device according to claim 1,wherein the nonlinear transmission line comprises a nonlineartransmission line selected from the group consisting of a gyromagneticnonlinear transmission line, a ferrite based nonlinear transmissionline, lumped element nonlinear transmission line, a parallel platesegmented nonlinear transmission line, and a magnetic lumped elementnonlinear transmission line.
 4. The high frequency electromagneticradiation generation device according to claim 1, wherein the antennahas an impedance less than about 300 Ohms.
 5. A high frequencyelectromagnetic radiation generation device comprising: a high voltageinput configured to receive electrical pulses having a first peakvoltage that is greater than 5 kV; a nonlinear transmission lineelectrically coupled with the high voltage input; a high voltage outputelectrically coupled with the nonlinear transmission line that radiateselectromagnetic radiation at a frequency greater than 100 MHz about avoltage greater than 5 kV; and a pulse recirculating circuitelectrically coupled with the high voltage input and the high voltageoutput, the pulse recirculating circuit configured to direct unradiatedenergy from the high voltage output to the nonlinear transmission line.6. The high frequency electromagnetic radiation generation deviceaccording to claim 5, wherein the pulse recirculating circuit comprisesa filter.
 7. The high frequency electromagnetic radiation generationdevice according to claim 5, wherein the pulse recirculating circuitcomprises at least one diode.
 8. The high frequency electromagneticradiation generation device according to claim 5, wherein the pulserecirculating circuit comprises a transmission line.
 9. The highfrequency electromagnetic radiation generation device according to claim8, wherein the transmission line comprises a delay line that introducesa delay of less than 500 ns in a pulse traveling through the pulserecirculating circuit.
 10. The high voltage nonlinear transmission lineaccording to claim 5, wherein the nonlinear transmission line comprisesa nonlinear transmission line selected from the group consisting of agyromagnetic nonlinear transmission line, an LC ladder nonlineartransmission line, a lumped element nonlinear transmission line, adielectric and/or capacitive lumped element nonlinear transmission line,a parallel plate segmented nonlinear transmission line, a magneticlumped element nonlinear transmission line.
 11. The high voltagenonlinear transmission line according to claim 5, wherein the highvoltage input is coupled with a nanosecond pulser.
 12. A methodcomprising: pulsing a high voltage pulser to produce a first pulse thathas a voltage greater than 5 kV and a pulse width less than 100 ns;radiating a first plurality of electromagnetic radiation pulses from thefirst pulse at a frequency greater than 100 MHz; pulsing the highvoltage pulser to produce a second pulse that has a voltage greater than5 kV and a pulse width less than 100 ns; and radiating a secondplurality of electromagnetic radiation pulses from the second pulse at afrequency greater than 100 MHz.
 13. The method according to claim 12,further comprising: recirculating at least a portion of the first pulsethrough one or more circuit elements to produce one or moreelectromagnetic radiation pulses of the first plurality ofelectromagnetic radiation pulses; and recirculating at least a portionof the second pulse through one or more circuit elements to produce oneor more electromagnetic radiation pulses of the second plurality ofelectromagnetic radiation pulses.
 14. The method according to claim 13,wherein the one or more circuit elements comprises a circuit elementselected from the list consisting of a diode, a filter, a delay line,and a nonlinear transmission line.
 15. The method according to claim 12,wherein the first plurality of electromagnetic radiation pulses isradiated from an antenna.
 16. The method according to claim 12, whereinthe first plurality of electromagnetic radiation pulses radiates about avoltage greater than 5 kV; and wherein the second plurality ofelectromagnetic radiation pulses radiate about a voltage greater than 5kV.
 17. A method comprising: pulsing a high voltage pulser to produce afirst initial pulse that has a voltage greater than 5 kV, a pulse widthless than 100 ns, and with a first energy; radiating a firstelectromagnetic radiation pulse from a portion of the first initialpulse at a frequency greater than 100 MHz; recirculating a portion ofthe first initial pulse; pulsing a high voltage pulser to produce asecond initial pulse that has a voltage greater than 5 kV, a pulse widthless than 100 ns, and with a second energy, the second energy less thanthe first energy; combining the second initial pulse with therecirculated portion of the first initial pulse to create a combinedsecond pulse; and radiating a second electromagnetic radiation pulsefrom a portion of the combined second pulse at a frequency greater than100 MHz.
 18. The method according to claim 17, further comprising:recirculating a portion of the combined second pulse; pulsing a highvoltage pulser to produce a third initial pulse that has a voltagegreater than 5 kV, a pulse width less than 100 ns, and with a thirdenergy, the third energy less than the first energy; combining the thirdinitial pulse with the recirculated portion of the combined second pulseto create a combined third pulse; and radiating a third electromagneticradiation pulse from a portion of the combined third pulse at afrequency greater than 100 MHz.
 19. The method according to claim 17,wherein the first initial pulse is propagated through a nonlineartransmission line, wherein the second initial pulse is propagatedthrough the nonlinear transmission line, and wherein the recirculatedportion of the first pulse is propagated through the nonlineartransmission line.
 20. The method according to claim 17, wherein theportion of the first initial pulse is recirculated through atransmission line that introduces a delay in the portion of the firstinitial pulse.